This invention relates to a method of, and a system for, adapting a network topology.
Connections between devices in a network can be represented by a network topology. This topology represents the connections between the different components in the network, and can be a physical topology representing actual physical connections between the components, or can be a logical topology representing how communications are permitted over the existing physical network.
One such network topology is the administration of the connectivity of a fibre channel storage area network. Such a network connects storage disk systems, storage controllers, storage virtualization servers and hosts using fibre channel switches and fibre optic cables. The components of the storage area network that are connected together are each given a unique “world wide node name”. An important element of a storage area network is increased reliability by the use of redundant components. To increase redundancy and throughput, each component is likely to support multiple fibre channel ports and each of these is given a unique “world wide port name”. To increase redundancy and throughput, each node is also likely to be duplicated and will share with its equivalent partner nodes the particular task in the storage area network, so there is likely to be two or more paired switches, pairs of storage virtualization nodes in an input/output group, paired storage controller front ends and so on.
In the administration of the storage area network connectivity, the goal is generally to configure for the maximum possible redundancy so there are as many as possible redundant paths between any two points. Most nodes will run intelligent multipathing software that will notice a point to point path failing and fail-over to using a second path that is still open. This is ideal from a system reliability point of view. However, the creation of redundancy via storage area network connectivity administration is a more skilful task that the simple describing/configuring of the point-to-point graph of the connectivity between hosts and storage nodes in the storage area network. A well configured storage area network also results in a graph of connectivity between port names that is much more complex than the equivalent simple non-redundant graph of connectivity.
The administration of a network topology that represents a storage area network is a non-trivial task. In particular, the addition or deletion of port connections in the storage area network, when carried out manually, is a process that is heavily prone to error.